The present invention relates to processing of cocoa. It particularly concerns processing cocoa mass to generate separated cocoa powder and cocoa butter, both at desirable quality levels and in desirable yields.
Cocoa beans may be processed into cocoa butter and cocoa powder. Cocoa butter represents a portion of the fat content isolated from the cocoa beans. The cocoa powder represents remaining solids, after processing to recover cocoa butter.
Cocoa butters are widely utilized food additives. For example, cocoa butter is used in the production of chocolate. Cocoa powder is also used as a food additive for flavor and color, for example, to produce chocolate flavored milk, cake mixes and brownie mixes.
In general, cocoa beans are harvested in tropical countries. Beans from different regions do provide somewhat different tastes or characteristics. For example, for chocolate, many European manufacturers prefer beans from Ghana and Nigeria (Ivory Coast) because of their flavor. For top quality chocolate, South American, West Indian and other so-called flavor beans are often used. The pressing industry may select beans containing fat with higher melting points, such as those obtained from Malaysia. Regardless of the source, the same general processing techniques have been used.
In typical processing, the cocoa beans are harvested within a husk. Typically, the beans are dried in the fields, and dehusked. The beans are then subjected to various forms of heating, for example to intense infrared treatment, to pop the shells and in some instances for microbiological control. The shelled beans are generally referred to as cocoa nibs. The nibs are separated from the shells, for processing.
In typical processing operations, the nibs are roasted and in some instances subjected to dutching (alkali treatment or alkalization). The nibs are then ground, often with significant generation of heat.
The grinding is generally done to provide a fineness in the mass such that there will be no grittiness felt in the mouth, when eating resulting products containing the cocoa powder. The grinding is normally carried out in a series of mills; for example, pre-grinding to a size of less than 300 microns using a hammer mill, blade mill, disc mill or ball mill, followed by fine grinding using a triple disc mill or staged agitator ball mills. In general, sufficient grinding is conducted so that the resulting cocoa powder, after separation of the cocoa butter, will have a particle size of less than 1 wt. % retained on a 200 micron sieve and less than 30% retained on a 30 micron sieve. A typical average particle size would be between 2 microns and 20 microns.
Some manufacturers do not grind the nibs sufficiently to achieve this fineness, but rather engage in further refinement with later processing steps.
In general, the mass which results from grinding of the nibs is referred to as xe2x80x9ccocoa massxe2x80x9d or xe2x80x9ccocoa liquorxe2x80x9d. At room temperature, it is a thick solid mass; however, when heated above the melting point of the fat it forms a viscous, flowable slurry. Typical cocoa liquors contain about 50-58% fat and 42-50% powder (or remaining solids), by weight. The moisture content of cocoa liquor is generally at a maximum of about 2.5%. The pH is typically within a range of 5.2-6.0. The shell content, by weight, is generally no more than about 1.75%. The fat content of cocoa liquor is that portion generally referred to as xe2x80x9ccocoa butterxe2x80x9d, after it has been separated from a remainder of the mass.
In general, about 30% of the world cocoa bean crop is converted into cocoa mass in a country where it is grown. This material is sometimes referred to as xe2x80x9coriginalxe2x80x9d liquor or mass. In later processing, such mass is not necessarily used alone, but sometimes is blended with mass or liquor from other sources.
In conventional xe2x80x9cpressxe2x80x9d processing, cocoa liquor is mechanically pressed, to physically xe2x80x9csqueezexe2x80x9d a portion of the fat out. In some instances the mass may be washed, to modify flavor or color. Generally up to about 80-85% of the fat content (of the 50-58%) can be removed from the cocoa mass, by mechanical pressing. This typically leaves a cake comprising about 10-20% butter (often 11-12%), by weight, the remaining comprising cocoa powder. Cocoa powder with a fat content of about 10% or below is often referred to as low-fat cocoa powder. The fat which is isolated by mechanical pressing is typically called xe2x80x9cpress butterxe2x80x9d.
The time and pressure it takes to remove the fat by pressing, to generate isolated press butter, increases substantially when the process is practiced to reduce the residue cake from about 20% fat content to about 11% fat content or lower. To reduce the fat content from 20% to about 10% may require twice as long of a processing (pressing) operation, as to reduce to 20%. Indeed, it may not be practical or even possible to get to less than about 5-9% fat, by weight, in the resulting cocoa cake, by conventional pressing techniques.
According to one report, whole cocoa beans have been processed without previous deshelling by continuous expeller techniques. The expeller cake and various resulting cocoa waste materials would then apparently be defatted by means of solvent extraction. The defatted residues from such a process, however, would be unlikely to be useful as food products, since they would contain large particles, such as shells and miscellaneous ditrious associated with the shells, which provide an unpleasant feel to the product. The isolated fat from such sources (which may include fats from portions of the cocoa bean other than just nibs) would also likely be of inferior quality.
Herein the term xe2x80x9ccocoa butterxe2x80x9d will be used to refer to the fat which is isolated from cocoa mass, during a separation process. Cocoa butter, which primarily comprises triglycerides of acids such as oleic acid, palmitic acid, and stearic acid, is a relatively valuable vegetable oil commodity. It is somewhat unique among vegetable oils, because of the combination of its taste, mouth feel and melt characteristics. These, in part, result from crystalline forms of some of its constituents, which provide for a sharp melting point just below body temperature. Also, the heat required to melt the crystals in cocoa butter results in a characteristic xe2x80x9ccoolingxe2x80x9d sensation in the mouth, a highly desired quality of cocoa butters when used as food additives.
The remaining mass resulting from pressing of the cocoa mass, is referred to herein as xe2x80x9ccocoa cakexe2x80x9d. As indicated above, with conventional press processing, the cocoa cake comprises about 10-20% cocoa butter, by weight. Again, this represents the (practical) maximum extent to which typical, conventional, mechanical pressing operations can remove cocoa fat from the cocoa liquor.
Typically, the resulting cocoa cake (after butter recovery) also comprises a useful commodity. It is generally ground into a powder and packaged for a variety of uses. For example, cocoa powder made in this manner is used as a flavorant (and for color) in such materials as cake mixes, frostings, cookies, chocolate and drink mixes.
Conversion of the cocoa cake to the cocoa powder is no trivial matter. Due to the fat content, typically 10% or greater, the cocoa cake after pressing will be a clumped-together mass. To convert it to a powder, it must be cooled sufficiently and maintained sufficiently cool, while it is broken up; and, in some instances it must be further ground and sieved, again without generation of sufficient heat to reclump, due to the fat content. In general it must be maintained below about 27-30xc2x0 C., or the fat content will tend to melt and generate clumping.
Cocoa beans have been processed by pressing generally in the manner described above for many decades. As indicated, the two principal commodities obtained are: the cocoa butter isolated from the pressing steps; and, the cocoa powder, typically containing about 10-20% cocoa fat by weight.
In some applications, the fat content (10-20%) of the cocoa powder has been found undesirable. These are applications in which it is desired that the ultimate food product which is manufactured contain relatively low amounts of various added fats or oils. In recent years, then, processes of reducing the fat content of cocoa powder have been examined. In general, fat-free cocoa powders, i.e., cocoa powders containing no more than about 0.5% by weight cocoa butter, have been generated by extracting the cocoa powder obtained after pressing, via a supercritical carbon dioxide extraction. The supercritical extraction reduces the residual fat content of the cocoa powder, leaving the powder defatted.
Techniques for processing cocoa mass are described. In general, the techniques concern processing cocoa mass in a manner including steps of: (a) extracting cocoa mass with solvent to provide a solvent phase containing dissolved cocoa fat and a residual solids phase comprising defatted cocoa solids; and, separating the solvent phase containing the dissolved cocoa fat from the solids phase. The process can be conducted in multiple stages of extraction/separation, with a final separation before isolation of product(s).
A variety of separation techniques can be applied. Certain preferred ones are described below.
In general, processing according to the present invention will be conducted under a pressure sufficient to allow for the solvent to be substantially in the liquid phase, while the process is conducted above the melting point of the cocoa fat. This will typically comprise processing at a temperature within a range of about 40-90xc2x0 C., and a pressure within a range of about 16 psia to about 580 psia, depending on the particular solvent chosen. For example, when butane is used, the pressure will typically be within a range of about 50 psia to about 200 psia.
Although a variety of solvents may be used, in general it is foreseen that solvent or solvent mixtures selected from propane(s), butane(s) and/or pentane(s) will be preferred. With respect to quality of isolated butter, from the extraction/separation, the most preferred solvent identified thus far, as indicated by the experiments below, is butane. Although various isomers can (in some instances) be used, generally the linear alkanes (n-propane, n-butane, n-pentane) are preferred.
Techniques according to the present invention can be readily applied to achieve, by extraction, removal of at least 95%, by weight, of all cocoa fat in the cocoa mass extracted. Indeed, they can be practiced to achieve extraction of at least 99% by weight, of all cocoa fat, in the cocoa mass, in many instances. In general, this requires appropriate amounts, or extent, of extraction. In some instances multiple stage extractions will be used to accomplish this. In at least some instances, such an extent of fat recovery can be achieved whether the fat content of the mass extracted is relatively high, i.e., greater than 45% (for example, 50-58%) or relatively low, i.e., 20-45% (perhaps due to some preprocessing).
In general, cocoa powders (or isolated solids) resulting from preferred practices of the present invention will contain no more than about 2%, and typically no more than about 1%, cocoa fat, by weight. Fat contents of less than 0.5%, by wt., are achievable. These latter cocoa powders may be especially useful in preparing food products to be designated as xe2x80x9cfat-freexe2x80x9d under the NLEA (Nutritional Labeling Education Act).
In general, when multi-stage extractions are conducted, it is typically preferable to contact the most defatted cake with the freshest solvent. That is, the preferred multi-stage extractions are conducted in a somewhat countercurrent fashion or form. Preferred processes will be conducted in such a manner that the fat is extracted relatively efficiently, for example through control of conditions, and relative amounts of solvent and solid phase, such that a concentration of fat in the solvent phase after a step (for example, including multiple stages) of extraction is at least 15%, preferably at least 25%, and most preferably at least 35%, by weight.
In general, preferred processes according to the present invention will involve extractions at pressures greater than atmosphere, typically about 50 psia to 200 psia (for butane) or 50 psia to 400 psia (for propane).
According to the present invention, preferred products are provided. These may comprise, in part, good quality (or better) cocoa butter achieved by the techniques; and, desirable cocoa powder products.